In a backlight module of the traditional LCD, as shown in FIG. 1, an optical sheet 102 is arranged on a back plate 101 and is positioned thereon by the following method: the back plate 101 has rivets 103 and the optical sheet 102 has openings 104 on corresponding positions; the rivets 103 on the back plate 101 and the openings 104 of the optical sheet 102 are coupled to each other.
In the backlight module, the positioning technical solution for the optical sheet 102 has shortcomings, as follows: (1) It needs to arrange the rivets 103 on the back plate 101; once the positions of the rivets 103 are biased, the rivets 103 could not align with the openings 104 of the optical sheet 102. Thus, the rivets 103 and the openings 104 of the optical sheet 102 cannot couple to each other, resulting in discard of the back plate 101 or the optical sheet 102, and material waste. (2) A success coupling requires that the optical sheet 102 and the back plate 101 match with each other, namely, if the optical sheet 102 wants to be successfully coupled to the back plate 101, the position and size of each rivet 103 on the back plate 101 must be designed according to the position and size of each opening 104 of the optical sheet 102; otherwise, if the back plate 101 wants to be successfully coupled to the optical sheet 102, the position and size of each opening 104 of the optical sheet 102 must be designed according to the position and size of each rivet 103 on the back plate 101. Hence, between different modules, the optical sheet 102 and the back plate 101 are incompatible (not universal).
Therefore, it is necessary to propose a new technique to solve these technical problems.